Construction equipment, such as earth-moving vehicles and the like, must be stabilized during construction or digging operations to limit movement of the equipment or vehicles. Typically, stabilization is provided by hydraulically actuated arms that extend from the vehicle and that have earth-engaging pads mounted on their distal ends. When the vehicle or equipment is moved into a working position, if extra stability is needed, the stabilizer arms are hydraulically operated to move from a retracted position, in which the arms generally extend upwardly and out of the way, to a user position in which the arms extend downwardly at an acute angle to the ground surface so that the pads contact the ground surface. When it is desired to move the vehicle, the arms are returned to the retracted position, and the vehicle is moved to a new operating location.
Reversible stabilizer pads for construction equipment, such as earth-moving vehicles and the like, are well-known in the prior art. Examples of such pads are found in U.S. Pat. Nos. 4,761,021 and 4,889,362. Such stabilizer pads generally have a first surface for engagement with a softer surface, such as gravel and soft earth, and a more resilient second surface on the opposite side of the first surface for engagement with harder surfaces, such as concrete or asphalt. Typically, the first surface includes flanges with grouser points that permit the pads to dig into the softer, unfinished surface formed by gravel or soft earth, to better anchor and stabilize the vehicle when encountering difficult digging conditions. The first surface is unsuitable for contact with a hard surface, since the grouser points could damage or mar the hard asphalt or concrete. The second surface of the pad typically is formed of a laminated, rubber pad for better stability on the more solid surface provided by concrete or asphalt. The stabilizer pad typically is pivotally mounted to the distal end of the hydraulically operated arm so that the pad may be rotated to contact the ground with either the first surface or the second surface.
U.S. Pat. No. 4,889,362 discloses a reversible stabilizer pad for earth moving vehicles having a generally flanged first surface for engagement with, for example, gravel and soft earth, and a resilient surface for engagement with, for example, concrete or asphalt. This patent describes the use of rubber pads on one side of the stabilizer pad for ground contact when the vehicle is on a finished surface, such as concrete or asphalt, and flanges with grouser points on the opposite side of the stabilizer pad for ground contact when the vehicle is on an unfinished but hard ground surface that requires that the pads dig into the surface in order to better anchor and stabilize the vehicle when encountering difficult digging conditions. The flange side of the pad is unsuitable for contact with a finished surface since it could damage and/or mar the finished surface. The stabilizer pad is pivotally mounted to the end of a hydraulically operated arm such that the pad may be rotated to contact the ground with either the rubber pad side or the flange side facing down to contact the ground surface. When the vehicle is moved into a working position, if extra stability is needed, the stabilizer arms, on which the pads are mounted, are hydraulically operated to move from a retracted position, in which the arms generally extend upwardly and out of the way, to a use position, in which the arms extend downward at an angle with the pads contacting the ground surface. When the vehicle is to be moved, the arms are lifted back to the retracted position, the vehicle is moved to a new operating location and the stabilizer arms are brought down into the use position again, if necessary.
In prior stabilizer pad constructions such as the one described in U.S. Pat. No. 4,889,362, there has been a tendency for the pad to self-flip when the stabilizer arm is lifted. This self-flipping generally occurs when the flange side is down such that the stabilizer pad flips from the flange side down to the rubber pad side down. This occurs because the rubber pad side is typically much heavier than the flange side. When the pad inadvertently flips sides, an operator must manually flip the pad down so that the proper side is facing down. Frequently, however, the operator does not realize that the pad has self-flipped or, even if the operator realizes it, does not bother to fix it. When this occurs, the vehicle is used with the wrong side of the stabilizer pad in contact with the ground surface, which could result in increased hazard as well as increased wear of the rubber pads, leading to premature need for replacement. The self-flipping of the pad can be remedied with a securing or engaging bolt that is required to be secured in each position of the pad and to be disassembled and re-secured when the position of the pad is to be changed. This becomes time consuming and furthermore may involve parts that are easily lost. Further, the operator simply may not use the securing pin or bolts.
U.S. Pat. No. 4,889,362 discloses an automatically operatable latch that is adapted to rotate into an engagement with the pad when the pad is in a ground engaging surface, and is furthermore adapted to automatically rotate by gravitational force out of engagement with the pad when the arm of the earth moving machine that supports the pad is lifted. In this way, when the support arm is lifted, the latch disengages from the pad and the pad is easily rotated to its opposite position. It has been found, however, that rocks, gravel and other debris frequently get caught in the automatic latch disclosed in U.S. Pat. No. 4,889,362 which can prevent the latch from releasing when the arm is lifted. In many stabilizer constructions, the pad must rotate to some extent when the arm is lifted in order to allow the piston of the arm to retract into the cylinder. Failure of the latch to release can result in damage to the arm or pad.
Accordingly, it is an object of the present invention to provide an improved stabilizer pad/arm construction for a vehicle.
A further object of the present invention is to provide a stabilizer pad/arm construction for an earth moving machine which will not flip sides unintentionally.
Another object of the present invention is to provide a stabilizer pad having improved balance to prevent unintentional flipping of the stabilizer pad.
Still another object of the present invention is to provide a stabilizer pad having an enlarged footprint, preferably using multiple resilient pads.